Table ii



United States Patent 3,135,756 s s-Punte ernnuarnqrma-rnnm'rnrnrt AonraTEs This invention is concerned with 2-(4-phenylpiperazinyl)-1-phenylethyl acetate of the structure,

which are relatively non-toXic and show desirable bronchodilator properties in the absence of cardiovascular side efifects.

While these compounds provide many unique structural distinctions relative to known bronchodilator agent in particular, the acetate conveys unique and desirable properties, insofar as eliminating the sustained hypotension and other cardiovascular side-effects noted with underivat led free hydroxyl compounds.

The acetate derivatives of this application are distinguished by the fact that a variety of other derivatives of the alcohohc group such as the propionate, butyrate, benzoate, carbarnate, and ethyl carbarnate fail to provide the same desirable pharmacological response.

(,ornpounds contemplated and indicated as within the scope of this invention are those wherein R is hydrogen, halogen, lower alkyl and aryl, and wherein R is selected from the group consisting of hydrogen, lower alkyl, lower alkox and halogen.

The compounds of this invention are strong bases and by virtue of this property can form salts with the nontoxic mineral acids, typified by hydrochloric, hydrobrornic, sulfuric acid, as well as salts of the orgmic acids, and the acidic Xanthines. In addition, the acetate compounds can be quaternized with such agents as methyliodide, diethylsulfate, allyl bromide, and ethyl brornoacetate.

Since the acetoxy bearing carbon atom is asymmetric, there is also contemplated the individual d and 1 forms in addition to the d1 racernate of the novel compounds of this invention.

The compounds may be prepared by condensation of the appropriately substituted phenylpiperazine with the 3,135,755 Patented June 2, 1964 requisite styrene oxide to yield the amino alcohol as shown in the equation below:

CH-CH2 The alcohol, in turn is acetylated to yield the required compounds through use of acetic anhydride or acetyl chloride.

An additional route involves the condensation of the substituted phenylpiperazine with a phenacyl halide to give the ketone which, in turn is reduced to the alcohol with sodium borohydride or by means of catalytic hydrogenation, as indicated in the equation below:

t RI o oniBr HN N@ The alcohols, in turn, are acetylated as described above. In general, it was convenient to use the styrene oxide method for compounds where R was hydrogen, and the phenacyl halide synthesis where R was a substituent other than hydrogen.

Compounds typifying the syntheses involved and the nature of the products embodied by this invention are shown in the tables below.

Intermediate Reactaizt [Ketones X=C 0-] Analysis, percent M.P., 0., RS. or Percent R1 B.P., 0. (mm. yield Formula Carbon Hydrogen Nitrogen pressure) Cale. Found Cale. Found Cale. Found 1 132-133 CnzHmCINzO 68:7 68.8 61 6,3 8.9 9 1 p-Cl.HBr 242-244 (A) 61 C18H20BTC1N20 54. 6 54. 8 5.1 5. 3 p-Br- 139- 0 cisHisBlNzo 7. 8 7. 8 p-Br.EBr 243-246 (1. (A)- 50 CisHzoBn-NzO 49.1 48. 9 4. 6 4. 6 6. 4 6.1 2,4-diCH -111 29 C2oH24N2O 77.9 78.1 7.8 7.6 9.1 9.1 p-C5H 196-198 (13)..-- 49 CnHnNzO 80. 9 80.9 6.8 6v 9 7.9 7, 6

See footnotes at end of table III.

TABLE II Intermediate Reactant [Alcohols X=-CHOH] Analysis, percent M.P., or Percent R1 B.P., yield Formula Carbon Hydrogen Nitrogen Cale. Found Cale. Found Cale. Found 78 C 1BHZ2N2O 76. 6 76. 6 7. 9 8. C gH2 C1N2O 8. 8 8. 58 Cl8H2lC1N20. 68. 2 68. 7 6. 7 6. 6 8. 8 8. 4 56 CmHmBrNzOl 59. 8 59. 8 5. 9 6. l 7. 8 7. 3 74 C20H2aN2O 77. 4 77. 3 8. 4 8. 4 9. 0 9. 0 56 C24H2aN2O 80. 4 80. 0 7. 3 7. 0 7. 8 7. 9 23 C1uH24NzO 77. 0 77. 1 8. 2 7. 9 9. 5 9. 5 47 C19H2 NzO. 9. 5 9. 5 5O C19H24N20. 9. 5 9. 6 60 C1BH21N20- 9. 5 9. 7 56 0131121010120 8. 8 9. 1 48 0131121010120-.. 8. 8 9. l 60 C13H2JC1N20 3. 3 9. 2 O-CH3OCaH4 80 Cl9Hfl{1 T702 9. U 9. 1 D' 3 6 4 10 CJBHMNZOB 9. 0 9. 0

Seeiootnotes at end of Table III. 7

TABLE I11 Final Product [uAcetates X= -CHOCOCHa-9] Analysis, Percent 1 M.P., C or Percent Formula Carbon Hydrogen Nitrogen b.P. C yield Cale. Found Cale. Found Cale. Found 113-115 (Q) 65 CH24N202----- 74. 0 74 4 7. 5 7 5 8.6 8. 5 132-134 .005)- 70 Cz1HzuN2O2 8.3 8. 2 186-190 (0.05) C22H2sN2O2 75.0 75. 4 8 0 8. 1 8. 0 7. 8 130-133 (D). 36 Cg5Hz7c1NzO2 70. 9 70. 6 6 6 6. 4 184-185 20 C19H23N3O2 70. 1 70. 2 7 1 6. 7 12. 9 13. 2 126-127 (B) 50 OZIHWNSOL 71. 4 71. 1 7. 7 7. 7 11. 9 12. 1 109-110 (C) 57 CzuH23C1N202- 7. 8 7. 9 118-119 (C) 72 C2 )H23B1'N20z 7. 0 7. 4 100-101 (C)---- 74 C2zH-2sN202 75.0 75.1 8.0 7. 9 8.0 8. 3 68 (C) 65 C21H25N2O2----- 74. 5 74. 6 7. 7 7. 8 8. 3 8. 2 0-CH3C5H4 99-101 (C).. 50 74. 5 74. 1 7. 7 7. 5 S. 3 8. 4 m-C S lE J 109-110 (G) 60 8. 3 8. 3 D- a a L 88-89 (C) 78 7. 7 7. 6 8.3 8. 2 1 5 4 90-91 (C) 4s C @H23C1N2Oz 7. 8 8. 0 m-ClCsH; 95-97 (0) 60 C20H73C1N202 66. 9 67. 0 6. 5 6. 5 7. 8 8. 0 D- Qe 4 123-124 (C) 48 C3nH23ClNzO2--- 66. 9 67. 1 6. 5 6. 2 7. 8 8.0 o-CHaOC5Hr- 200-206/0.00 57 C H NZOLH" 71. 2 71. 6 7. 4 7. 6 7. 9 7. 9 P- aOCe 4--.- 87-88 (C) 66 C21HzaNaO2- 71.2 70. 8 7. 4 7. 2

B Melting points are not corrected and Were determined on a Fisher-Johns melting point block. Solid compounds were recrystallized fromethanol unless otherwise shown. A

e Reactant is 1-phenyl-2-methylpiperazine.

a X: OHOCONH b X: -OHOC0NHC2H b Hydro chloride of compound. 1 X CHOCOCeH compound isolated as hydrochloride.

The preferred embodiment of this invention is directed especially to compounds wherein the R group is unsubstituted or substituted as halogen and R group is varied as hydrogen, methyl, and dimethyl.

Examples typifying the syntheses employed in the preparation of compounds of this invention which are in no sense limiting are given below; also presented is synthesis of typical intermediates, and closely related analogs of the compounds of this invention introduced for purposes of comparison. EXAMPLE 1 2- (4-Phenylpiperazinyl) -]-Ph enylethan0l A mixture of 37.7 g. (0.24 mole) of l-phenylpiperazine and 19.2 g. (0.16 mole) of styrene oxide in 100 mls. of ethanol was maintained under reflux for 7 hours. After storage at 20 for 20 hours the formed precipitate was separated and recrystallized (ethanol) to give 34 g. (78%), M.P. 113,

EXAMPLE 2 2-(4-Phenylpiperazinyl) -1-Phenylethyl Acetate 2-(4-phenylpiperazinyl)-1-phenylethanol (56.0 g., 0.2

RS. Recrystallizing solvent =mcthanol; B =acetonitrile; C =hexane; D =acetone. d X= -CHOCOCzH5- B X= -CHOCOCaH n mole) was added to a stirred solution of 44.0 g. (0.22 mole) of acetic anhydride and 16 g. (0.2 mole) of pyridine in 250 mls. of acetonitrile and the reaction mixture heated under reflux for 9 hours. After removal of volatiles at diminished pressure, the residue was granulated with cold dilute sodium hydroxide. The product was separated,

dried, and recrystallized (hexane) to give 42 g. (65%),

Treatment of a methanol solution of the free base with a methanolic solution of an equivalent quantity of hydrogen chloride gave the title compound hydrochloride.

EXAMPLE 3 2- (4-Phenylpiperazz'nyl) -1-Phenylethyl Propionate EXAMPLE 4 2-(4-Phenylpiperazinyl)-1 -Phenylethyl n-Butyrate A mixture of 2-(4-phenylpiperazinyl)-1-phenylethanol (7.0 g., 0.025 mole), 7.6 g. (0.025 mole) of n-butyric anhydride and 50 mls. of acetonitrile Were heated under reflux for 19 hours. The solvent was removed at diminished pressure, and the residue of product suspended in dilute sodium hydroxide and extracted into ether. After drying (magnesium sulfate), evaporation of solvent and distillation, there was obtained 4.4 g. (50%) of product, B.P. 186-190 (0.05 units).

EXAMPLE 5 1 (4-Phenyl pi perazinyl -Phenylethyl Benzoate Hydrochloride A cooled solution of 8.9 g. (0.03 mole) of 1-(4-pheny1- piperazinyl)-1-pheny1ethanol in 25 mls. of acetonitrile was treated with 4.2 g. (0.03 mole) of benzoyl chloride. After 4 days at 20, the product was separated and recrystallized (acetone) to give 4.5 g. (36%), Mi. 130-133.

EXAMPLE 6 2- (4-Phenylpiperazihyl -1 -Phenylethyl Carbamale A cooled solution of 8.5 g. (0.03 mole) of 2-(4-phenylpiperazinyl)-1-pheny1ethanol in 20 mls. of pyridine was treated with 4.7 g. (0.03 mole) of phenyl chloroformate and stirred for 3 hours at 20. After addition of 30 mls. of water, and extraction with ether, the ether phase Was successively washed with saturated aqueous sodium bicarbonate and saturated aqueous sodium chloride and then dried (magnesium sulfate).

The dried ether solution was added dropwise, with stirring, to 300 mls. of liquid ammonia and stored 16 hours. After evaporation of the ammonia, the residue was treated with 100 mls. of ether and 50 mls. of water.

The product was obtained upon evaporation of the ether phase, recrystallized (ethanol) to give 2.09 g. (20%), M.P. 184-1855 EXAMPLE 7 2-(4-Phenylpiperazinyl) -1-Phenylethyl-N-Ethylcarbamate A mixture of 2-(4-phenylpiperazinyl)-1-phenylethanol (4.8 g., 0.017 mole) and 1.2 g. (0.017 mole) ethyl isocyanate was maintained under reflux in a bath at 125 for 1.25 hours. When cool, the formed product was recrystallized (acetonitrile) to give 3.0 g. (50%), Ml. 126-127".

EXAMPLE 8 1 -(p-Chl0r0p11enacyl)-4-Phenylpiperazine 2-(4-Phenylpiperazz'nyl)-1-(p-Chlor0phenyl) ethanol Sodium borohydride (0.65 g., 0.017 mole) was added in small portions to a suspension of 11.9 g. (0.03 mole) of l-(p-chlorophenacyl)-4-phenylpiperazine in 100 mls. of ethanol previously rendered basic with aqueous sodium hydroxide. After storage at 20 over 18 hours, the reaction mixture was acidified with 3 N hydrochloric acid and then made hasic with aqueous sodium hydroxide.

The formed product was separated and recrystallized (ethanol) to give 5.5 g. (58%), MP. 154-155.

EXAMPLE 10 2(4-Phenylpiperazinyl)-1-(p-Chl0rophenyl)Ethyl Acetate 2-(4-phenylpiperazinyl) 1 (p chlorophenyl)ethanol (3.2 g., 0.01 mole), 20 g. (0.2 mole) of acetic anhydride and 25 mls. of acetonitrile were heated under reflux for 9 hours. After removal of solvent and excess anhydride at diminished pressure, the residue was recrystallized (hexane) to give 2.0 g. (57%) of product, MP. 109- 110.

EXAMPLE 11 2-[4-(o-T0lyl)Piperazinyl] -1-Phenylethanol A solution of 9.6 g. (0.08 mole) of styrene oxide and 14.1 g. (0.08 mole) of 1-(o-tolyl)piperazine in 50 mls. oi ethanol was heated under reflux for 9 hours. After removal of solvent and unreacted starting material at diminished pressure, the residue of product was recrystallized (ethanol) to give 11.0 g. (47%), melting at 116- 117.

ExAMPLE 12 2- [4- (o-Tolyl Piperazinyl] -1 -Phenylethyl Acetate A mixture of 4.5 g. (0.015 mole) of 2-['4-o-tolyl)- piperazinyl]-1-pl1enylethanol, 20 g. (0.2 mole) of acetic anhydride and 25 mls. of acetonitrile were heated under reflux for 9 hours. After removal of solid and excess acetic anhydride at diminished pressure, the residue was recrystallized (hexane) to give 2.5 g. (50%) of product, Ml. 99-1 01".

EXAMPLE 13 1 (2,4-Dimethylphenacyl -4-Phenyl pi perazine A solution of 12.8 g. (0.08 mole) of l-phenylpiperazine in 50 mls. of isopropyl alcohol was maintained at 65-70 during the addition of a solution of 14.6 g. (0.08 mole) of 2-chloro-2',4'-dimethylacetophenone in mls. of isopropyl alcohol. After heating under reflux for 15 minutes and cooling, the formed precipitate was separated, suspended in cooled, dilute aqueous sodium hydroxide to precipitate the product which was recrystallized (ethanol) to give 7.0 g. (29%), MP. -111.

AnaL-Calcd. for C I-1 N 02 C, 77.9; H, 7.8; N, 9.1. Found: C, 78.1; H, 7.8; N, 9.1.

EXAMPLE 14 2-(4-Phenylpiperaziizyl) -Z-(2,4-Dimezhylphenyl) I Ethanol Sodium borohydride (0.80 g., 0.021 mole) was added in small portions to 7 g. (0.022 mole) of 1-(2,4-dimethylphenacyl)-4-phenylpiperazine suspended in 70 mls. of ethanol, previously rendered basic with dilute aqueous sodium hydroxide. After storage at 20 for 18 hours, the mixture was acidified with dilute hydrochloric acid, and then made basic again with aqueous sodium hydroxide. Filtration of the solid and recrystallization from ethanol gave 5 g. of product (74%), MP. 139-140.

EXAMPLE 15 2-(4-Phenylpiperazinyl) -1-(2,4-Dimethylphenyl) Ethyl Acetate 2 (4 phenylpiperazinyl) 1 (2,4 dimethylphenyD- ethanol (3.1 g., 0.01 mole), 20 g. (0.2 mole) of acetic anhydride and 25 mls. of acetonitrile were heated under reflux for 8 hours. After evaporation of solvent and excess acetic anhydride, the residue was suspended in dilute sodium hydroxide, filtered, dried and recrystallized (hexane) to give 2.6 g. (74%) of product, M.P. 100- 101.

Upon addition of an equivalent of malic'acid to'a' methanol solution of the product, the malic acid. salt is obtained. H

The compounds of this invention may be administered in the form of tablets and capsules containing from -50 mg. of the active ingredient prepared in the conventional manner or in sustainedrelease forms, as well as elixirs, suspensions and other similar pharmaceutical dosage forms. For parenteral administration, the compounds desirably as their salts, may be incorporated in solution, in a non-toxic vehicle and sterilized, preferably by filtration. In addition, the compounds can be formulated as an inhalation aerosol or provided in a form for dispensing by atomizers, nebulizers, and similar devices.

To establish the elfectiveness of the compounds of 7 this invention, the following tests were employed.

Guinea pigs of either sex are selected on the basis of sensitivity (demonstrated by collapse) to exposure to aqueous 0.2% histamine aerosol under standard conditions for .3-5. minutes. Sensitive animals are allowed to recover for 24 hours. At the end of the recovery period, test compound is administered, either orally or subcutaneously, and 90 minutes later the pigs are reexposed to the aerosol. Those pigs not collapsing in 5 minutes are considered protected. Six pigs are studied per dose level and the dosage level plotted against the percent of pigs protected, and the effective dose providing 50% protection (ED is established.

In another test, fed and watered guinea pigs of either sex are selected on the basis of sensitivity (manifested by collapse in 5 minutes) to exposure to an aerosol of 1% acetylcholine bromide in saline at 5.8.lbs./in. (300 mm. Hg) driving pressure in a suitable chamber. Sensitive animals are allowed to recover for 2-4 hours. At the end of this time, test drug is administered by the desired route and 90 minutes later the pigs are re-exposed to acetylcholine bromide aerosol in the chamber under the standardized conditions. Those pigs which do not collapse within 5 minutes are considered protected. Six pigs are studied per dose level, and results are established as described for the histamine test.

Whereas such procedures established the potent bronchodilator activity of the compounds, a variety of standard procedures showed that compounds of this invention were relatively non-toxic, and without the undesirable cardiovascular, and central nervous system side efiects.

It is to be understood that the invention is not to be limited to the exact details of operation or exact compounds shown and described as obvious modifications and equivalents will be apparent to one skilled in the art and the invention is, therefore, to be limited only by the scope of the appended claims.

We claim:

the formula ing of hydrogen, lower alkyl, lower alkoxy, phenyl, and

halogen.

2. The compound 3. The compound 4. The compound 5. The compound 6. The compound O-(HJCH3 7. Nontoxic acid salts of the compounds of claim 1. 8. Quaternary ammonium salts of the compounds of claim 1.

References Cited in the file of this patent UNITED STATES PATENTS 2,849,306 Searle Aug. 26, 1958 2,854,470 Jacob et al Sept. 30, 1958 2,945,860 Schmidt et al. July 19, 1960 FOREIGN PATENTS 332,664 Switzerland Oct. 31, 1958 OTHER REFERENCES 1 Hampton et al.: Am. Chem. Soc. Jour., vol. 59, pp. 

1. THE COMPOUND OF THE FORMULA 